Control circuit for engine starting and ignition system



Sept 24, 1957 D. c. REDlcK 2,807,729

CONTROL CIR-CUIT FOR ENGINE STARTING AND IGNITION SYSTEM Fild NV. 17, 1954 2 Sheets-Sheet 1 F l'g.

INVENToR. David C. Re dick BY M His Attorney Sept. 24, 1957 D. c. REDlcK 2,807,729

CONTROL CIRCUIT FOR ENGINE STARTING AND IGNITION SYSTEM Filed NOV. 17, 1954 2 Sheets-Sheet 2 l IO 57 T Il Fig. 2

INVENToR. David C. Re dic/r H/'s Attorney United States Patent 'coN'rnoL CIRCUIT FORNGINE STARTING AND IGNIrIoNMsYsTEM AppiicaaniNvember-17; 1954; Sent-imo. 469,397` s Claims., (C1. .29o- 38)1 rhe'. invention: relates to. electric'. circuits for internal combustion engines'` andl is particularly.y concerned with the controlI of current in an ignition circuittherefor. v It is well known, that--thecurrent' requirements in ignition .circuits for internalcombustioniengines vary over the entirerange of:operationofgtheengine. For example, the requirements during periods; when the. engine is operating-unden-load atL ai highr.. p. m., or during. starting periods are greater. than'thecurrent requirements duringl normal operational periods.:

It is an object therefore-of, thexpresenti invention to increase the current in an ignition'rsystem.. during cranking periodsand whenthe engine operationV exceedsa predetermined conditionof load and speed.

Further-objects land advantages; of the present invention will-be apparent.- fromthetollowing.description, ref'- erencebeing had to the. accompanyinggdrawings wherein av preferregdtembodiment of the; present-invention isclearly. shown.

In the drawings Figure l. illustratesa wiref-.di'agr'amof theicircuitcon-v nections of one embodiment of an ignitioncircuit;according rto .the present` invention..

Figure 2 illustrates awire diagram ofanother modification .A of` an.Y ignition. circuit according tot the: present. in

vention..

It iswell known that averyheavy-,current'is required lto operate the starting motorv forcrankingan internall combustion. engine. during1 starting.- periods'. This causesV present. day-high. compression. engines, arev of `acritical nature and if the normal current is of an excessvalue, thepoints will quickly burn or; otherwise deteriorate. On the other hand, any reduction ofthe system voltage and current. will reduce the voltage` andcurrent to the-primary ignition. coil. winding and .maketor more ditlcult starting; It is furtherknown that under various conditions of op` eration, more particularly when the engine is operating at close to theifullopenthrottle position at a high-speed,- the ignition current requirements are increased. The present invention isdirected to theeliminationy of the above difficulties and will provide an ignition system wherein a higher current will be available to the-ignition sparkplugsonly'during the'starting periods andy when the engine isoperating'under heavy loads` and at ahigh rateof speed."

Referringnowdo the drawings, the. numeral designates acurrent source such as a storage battery which is grounded at 11. The battery 10 is connected by a lead 12 with an electromagnetic switch 13 which includes stationary contacts 14 and 16 and a movable contact 15 attached to a solenoid armature 17. Contact 16 is electrically connected to a starter motor 18 which is grounded.

'2,807,729 Patented Sept. 24, 1957 flice 2; Theelectro-magnetic switch 131 includes a winding 20 which: attracts the'armature-17to'n1ove contact 1-5'into a circuitI closingposition in. which the motor 18" is connected with the batteryl.

The battery 10'is alsoconnected by a lead 25 to the stationary. contact 26 of ak manually operated key switch S which may be of the type disclosed in U. S. Patent 2,655,570; and whichhasbeen assignedtosthe assignee of the present invention. Thisl switch Sprovides at least threey positions; namely, Off, Run,. and Start. In the presentinstance theswitch isshowndiagrammatically and includesramovable contactr30 of triangular form having three contact bosses, not.` shown. The movable contact bosses cooperate with the stationaryv contacts 26, 28' and 29', which` are connectedasfollows: contact Z6 is connected to.- the battery 10i' by leadi 25, contact 28 is connected by a lead. 32A through aneutralsafety switch 33, whichmay be of any suitable type, toa terminal'35 which is connectediwithzcoillZO and thecontact 29 is connected by al lead 36to aterminal 41 of resistance unit 40'which wille be hereinafter` described; The other terminal' 43 of thefresistance'unit 40`is connectedv through a junction 55 to oneendi of the-primary winding 42 of ignition coil 45. The other end of the-primary winding' 42 is connected withA a timer. mechanism, of conventional form, which includes. a fixed'contactl and a movable contact with the movableA contact groundedatv 1-1. A- secondary winding 461of coil: 45"is inductably associated with the primary winding.y 42 andi is electrically connected by a conductor 48fwithaA rotor-49loff`a;distributor which includes a plu rality of spaced terminals 51 which are connected throughVA spark plugs 52, diagrammatic'ally shown, to groundv 11.

From the juncture 55, torwhich terminal 43ofv the resistance unitc40fisconnected, a conductor 56 leads to a terminal 57' which is-arranged to be engaged'by themova- 'ble contact 15 wheneverthel latter bridgesy contacts 14` and: 16i

is closed-inthestartiposition. p

Theoperation` of the circuitf during starting when the neutral safety switch 33 is in the closed pos'itionis as follows: whenthe switch Sis moved manually tothe position. shown in full:y lines, the movable contact 30 will bridge contacts 26, 28 and29 In this position the battery will be connected to the ignition' terminal contact 29 and the .terminal 28- so that current will ilow from the. battery to winding'20 to attract thea-rrnature 17 and causethe movable contact to bridge contacts 14,y 57 andt16. When this occurs, the'resistance-unit 40-will'be shunted or short.

circuitediso that as the engine is being cranked, current will pass through the-shunt circuit including wire 56' and.

It is well known that if` the enginespeed and load is.

increased,"the ignition requirements-also are increasedV and that the; manifoldfvacuurnof-the-engine is decreased; The present invention is primarily directed to a method whereby an increased current is provided to the ignition system during the periods when the engine is operating under a load at high speed or under a heavy load at low speeds. The resistance unit 40, as shown in Figure 1, is provided with a pair of resistances 60 and 62 which are The'leadl 56 provides av shunt circuit that is. adapted totcut out'resistance unit 40when the Switch S in series in the circuit between terminals 41 and 43. Both of these resistances 60 and 62 are shunted out by conductor wire 56 during the cranking periods as heretofore described. When the engine is in normal operation, both of these resistances 60 and 62 are in circuit so as to limit the current to the primary winding 42 of coil 45. When the engine throttle opening exceeds a predetermined amount and the manifold vacuum is decreased to a predetermined value as, for example, in the order of 8 or l0 inches of mercury, a switch 64 which is normally open and connected with the intake manifold of the engine is caused to close. The switch 64 is of any well known pressure responsive type calibrated for the application involved and connected to close a circuit whenever the engine vacuum decreases below a predetermined value. The closing of switch 64 will shunt the resistance 60 from the ignition circuit so that more current will be available to the primary winding 42 and thereby increase the strength of the sparking impulses to spark plugs 52. In

Figure 2 a resistance 66 and 68 which comprises the resistance unit 40 are in parallel. Resistance 66 is of a higher ohmic value, i. e., 6.25 ohms, than the resistance 68 which may have a value of 1.8 ohms. As heretofore described, switch 64 is responsive to the manifold vacuum and is normally open so that during normal engine operations all of the ignition current will pass through resistance 68 except when the resistance unit 40 is shunted during the starting periods. When, however, the manifold vacum is sufficiently decreased switch 64 will close and, resistance 66 will be placed in parallel with resistance 68 so as to reduce the overall ohmic resistance value of resistance 40 and, thereby provide an increased current to the primary winding 42 for the purposes heretofore set forth.

From the above it is apparent that the ignition circuit according to the present invention will not only provide for a greater ignition current to the engine during the starting periods but will also provide a higher current when the engine is operating under load at approximately the full throttle position or when the engine is under a heavy load at low speeds. This increased ignition when the engine is operating at full throttle will result in an increased economy of operation and an improved engine performance.

While the embodiments of the present invention as herein disclosed constitute preferred forms, it is to be understood that other forms might be adopted.

What is claimed is as follows:

l. In a starting and ignition apparatus for an internal combustion engine that is subjected to variable operating conditions, the combination comprising: a dynamo electric machine for starting said engine, a storage battery for supplying current through a circuit to said dynamo, an ignition coil having a primary winding connected to the battery, a current limiting resistance in circuit between said battery and the primary of said coil, means connected with the circuit to the dynamo for shunting out said resistance when the dynamo is supplied with current from said battery, and a second means responsive for shunting at least a portion of said resistance when a predetermined intake vacuum condition of said engine is achieved.

2. In a starting and ignition apparatus for a variable speed internal combustion engine, the combination comprising: a dynamo electric machine for starting said engine, a storage battery for supplying cuirent through a circuit to said dynamo, an ignition coil having a primary winding connected to said battery, a current limiting resistance in circuit between said battery and the primary of said coil, means connected with the circuit to the dynamo for shunting said resistance when the dynamo is supplied with current from said battery, and a second means responsive to intake vacuum of said engine for shunting at least a portion of said resistance when the vacuum of said engine describes below a predetermined value.

3. In a starting .and ignition apparatus for an internal combustion engine that is subjected to a variable operation of speed and load, the combination comprising: a dynamo electric machine for starting said engine, a storage battery for supplying current through a circuit to said dynamo, an ignition coil having a primary winding connected in a circuit with said battery, a pair of current limiting resistances in said coil and battery circuit, means connected with the dynamo circuit for shunting both of said resistances when the dynamo is supplied with current from said battery, and a second means responsive for decreasing the effect of said pair of said resistances when the eng-ine vacuum is decreased below a predetermined value.

4. The combination as set forth in claim 3 wherein the pair of resistances are connected in series in the circuit between said coil and battery and said second means shunts one of said resistances.

5. The combination as set forth in claim 3 wherein said pair of resistances are connected in parallel with each other and wherein the second means mentioned closes a circuit to one of said pair of resistances.

6. In an ignition system for an internal combustion engine that is subjected to variable operating speeds and loads, the combination comprising: a storage battery, an ignition coil having a primary winding connected in circuit with said battery, a resistance in said circuit, and a means responsive to a predetermined condition of operation for varying the eiective value of said resistance in sa-id circuit, wherein said resistance in said circuit includes a pair of resistances which are in series in the circuit between said coil and said battery, and said means shunts one of said resistances.

7. In an ignition system for an internal combustion engine that is subjected to variable operating conditions of load and speed, the combination comprising: a storage battery, an ignition coil having a primary winding connected in circuit with `said battery, a pair of resistances in said circuit, and a means for decreasing the effective resistance Values of said pair of resistances in response to a predetermined condition of operation of said engine, wherein one of said pair of resistances is connected in parallel with the other of said pair of resistances by said means closing a circuit to said rst mentioned resistance.

8. In a method for increasing the actuation of a primary winding of a coil for an ignition system for an internal combustion engine during predetermined operating conditions, the steps comprising; providing a resistance in the circuit between the primary winding and a storage battery, shunting out the resistance when said battery is supply-ing current to a dynamo electric machine that is used to start `the engine, and reducing the effective ohmic value of the resistance when lthe engine intake vacuum is decreased to a predetermined value.

References Cited in the lile of this patent UNITED STATES PATENTS 1,214,555 Leece Feb. 6, 1917 1,266,898 Alden May 21, 1918 1,769,150 Mallory July l, 1930 2,037,059 Beltz Apr. 14, 1936 2,655,570 Brown et al. Oct. 13, 1953 

